cargo-kconfig 0.0.4

/*
 Cargo KConfig - KConfig parser
 Copyright (C) 2022  Sjoerd van Leent

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it under the terms of the GNU General Public License as published by
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The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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*/

use std::{iter::Peekable, rc::Rc};

use kconfig_represent::ConfigRegistry;
use proc_macro::{token_stream::IntoIter, Delimiter, Group, Spacing, TokenTree};

use super::{comp::Comparison, tag_registry::TagRegistry, util::parse_string};

#[derive(Clone)]
pub(crate) struct Eval {
    config_registry: Rc<ConfigRegistry>,
    group: Group,
}

impl Eval {
    pub(crate) fn new_tagged(tag_name: &str, group: &Group) -> Self {
        let config_registry = TagRegistry::get_config_registry(tag_name);
        Self::new(&config_registry, group)
    }

    pub(crate) fn new(config_registry: &Rc<ConfigRegistry>, group: &Group) -> Self {
        Self {
            config_registry: config_registry.clone(),
            group: group.clone(),
        }
    }

    pub(crate) fn eval(&self) -> ValueRef {
        match self.group.delimiter() {
            Delimiter::Parenthesis => {
                let tokens = self.group.stream();
                self.evaluate_tokens(&mut tokens.into_iter().peekable())
            }
            _ => panic!("Expected (, found {}", self.group.to_string()),
        }
    }

    fn evaluate_tokens(&self, iter: &mut Peekable<IntoIter>) -> ValueRef {
        let lhs = match iter.next() {
            Some(tt) => match tt {
                TokenTree::Group(_) => self.eval(),
                TokenTree::Ident(i) => {
                    let s = i.to_string();
                    if s == "true" {
                        ValueRef::Boolean(true)
                    } else if s == "false" {
                        ValueRef::Boolean(false)
                    } else {
                        ValueRef::Config((s, self.config_registry.clone()))
                    }
                }
                TokenTree::Punct(p) => {
                    panic!(
                        "Expected group, identifier or literal, not: {}",
                        p.to_string()
                    )
                }
                TokenTree::Literal(l) => {
                    let content = l.to_string();
                    if content.starts_with('"') {
                        ValueRef::String(parse_string(&content))
                    } else {
                        match content.parse::<i64>() {
                            Ok(value) => ValueRef::Int(value),
                            _ => panic!("Literal value {} could not be parsed", content),
                        }
                    }
                }
            },
            None => panic!("End of input not expected"),
        };

        let comp = match iter.next() {
            Some(tt) => match tt {
                TokenTree::Punct(p) => match p.spacing() {
                    Spacing::Alone => Comparison::single(&p),
                    Spacing::Joint => match iter.peek() {
                        Some(peeked) => match peeked {
                            TokenTree::Punct(p2) => Comparison::dual(&p, p2),
                            _ => Comparison::single(&p),
                        },
                        None => Comparison::single(&p),
                    },
                },
                _ => panic!("Expected ==, !=, <, <=, >=, >, &&, ||"),
            },
            None => Comparison::None,
        };

        match comp {
            Comparison::Lt | Comparison::Gt | Comparison::None => (),
            // Since values have been peeked only in the case of dual
            // operator, now actually advance the iterator.
            _ => {
                iter.next();
                ()
            }
        }

        match comp {
            Comparison::None => lhs,
            _ => {
                let rhs = self.evaluate_tokens(iter);
                comp.compare(lhs, rhs)
            }
        }
    }
}

#[derive(Clone)]
pub(crate) enum ValueRef {
    // Extracted from an identifier (unless exactly "true" or "false")
    Config((String, Rc<ConfigRegistry>)),

    // Extracted from an identifier
    Boolean(bool),

    // Extracted from a literal are string or int
    String(String),
    Int(i64),
}

impl ValueRef {
    pub(crate) fn as_value(&self) -> Value {
        match self {
            ValueRef::Config((symbol, config_registry)) => {
                let value = config_registry.config_value(symbol);
                Value::String(value)
            }
            ValueRef::Boolean(b) => Value::Boolean(b.clone()),
            ValueRef::String(s) => Value::String(s.clone()),
            ValueRef::Int(i) => Value::Int(i.clone()),
        }
    }

    pub(crate) fn as_bool(&self) -> bool {
        self.as_value().as_bool()
    }

    pub(crate) fn as_string(&self) -> String {
        self.as_value().as_string()
    }

    pub(crate) fn as_int(&self) -> Option<i64> {
        self.as_value().as_int()
    }
}

#[derive(Clone)]
pub(crate) enum Value {
    String(String),
    Boolean(bool),
    Int(i64),
}

impl Value {
    pub(crate) fn as_bool(&self) -> bool {
        match self {
            Value::Boolean(b) => b.clone(),
            Value::String(s) => s != "" && s != "n",
            Value::Int(i) => i.clone() > 0,
        }
    }

    pub(crate) fn as_string(&self) -> String {
        match self {
            Value::Boolean(b) => match b {
                true => "y".to_owned(),
                false => "n".to_owned(),
            },
            Value::String(s) => s.clone(),
            Value::Int(i) => i.to_string(),
        }
    }

    pub(crate) fn as_int(&self) -> Option<i64> {
        match self {
            Value::String(s) => match s.parse::<i64>() {
                Ok(v) => Some(v),
                _ => None,
            },
            Value::Boolean(b) => match b {
                false => Some(0),
                true => Some(1),
            },
            Value::Int(u) => Some(u.clone()),
        }
    }
}